Finned tube construction



Oct. 7, 1952 J. s. NEWLlN FINNED TUBE CONSTRUCTION Original Filed July 23, 1948 Patented Oct. 7, 1952 UNITED STATES earsm'r i FINNED TUBE cons'rnnorron John Shipley Newuh, Paouja; team toMer chant & Evans Company, Philadelphia; Pa.,.a. corporation of ljennsylvania. I

Original application July. 23,: 1948,- Serial 'No..

40,389, now; Patent No. 2,532,239, dated Novem her; 28, 1950;; Divided and this application No-- vember 22, 1949, Serial No- 128,873. I a

The present invention relates to an improved finned tube construction and is a; divided application from the parent application Serial 'No. 40,389, filed July 23, 1948, now Patent #2,532,239, issued November 28, 1950.

Although the prior art contains many forms of finned tubing in which a length of tubing is helically wound with a strip of heat-radiating material, many of these devices have contained inherent objections. In the first place, the conventional winding machine is complicated and expensive; the rate at which the machine could wind tubing has been relatively slow; the heat transfer, which in turn depends upon the surface of the fin, has been inefiicient; and the product has been unable to withstand. hard usage.

A primary object of the invention therefore, is to provide an article of manufacture characterized by a fluted fin, the fin beingsmooth around its outer periphery and having feet at the base of the formed leg pressing the flutes into tight overlapping relationship to extend from either side of the fin, thereby providing maximum heat transfer surface, extreme fin rigidity, and excellent conductivity between the tube and the fin.

Further objects will be apparent from the specification and drawings in which:

Fig. l is a perspective of a length of finned tubing as wound on the machine;

Fig. 2 is a longitudinal section of the finished product of Fig. 1;

Fig. 3 is an enlarged perspective of the fin as it is being wound on the tubing;

Fig. 4: is a section as seen along the line 4-4 of Fig. 3; and

Fig. 5 is a transverse sectional view as seen at 5-5 of Fig. l.

A finned tube assembly in accordance with the invention is characterized by a helical fin iii wound tightly around the periphery of a length of tubing H. The finned material I!) is formed from a strip of flat sheet material characterized by relatively good ductility.

The strip material I0 is first crimped along one edge thereof to provide a series of crimps or folds l2, [2 as shown in Fig. 3. The opposite edge of the strip is then tightly gripped between two rollers in a revolving head of a winding machine and wiped around the periphery of the tubing which may be held stationary. This wiping action under controlled radial pressure provides a plurality of axially extending feet l3, !3 at the base of the fin. Furthermore, it also tends to thin the strip material around itsouterfperiphery and toincreasej theflthickness of thefin in the area, near the base. This 'gives a tapering cross-sectional area for the fin. The feet l3,l3 tightly overlap each other and tend'to flow helically around tube H in a direction opposite to that in which the strip material has been applied.

I have found that a plurality of axial flats l4, i l on the tubing enhance the ability of the finned material to remain in excellent contact with the periphery of the tube, thereby preventing any tendency to unwind and also improving the heat transfer properties of the finished article. The supporting area. and rigidity provided have been found to eliminate in many cases the necessity for any soldering or attachment of the fin to the tubing, since it exhibits no tendency to become loose or to unwind. The large contact area between the fin and the periphery of the tubing assist in the above desirable result as well as substantially increasing the conductivity at the base of the fin. As the heating progresses radially outward, the material in the fin decreases and the surface area increases so that a remarkably efficient transfer is obtained.

The finned tube product described herein may be wound in any desired manner but it will be understood that a preferred machine for fabri-F eating the product is described and claimed in the parent application referred to above, which is incorporated herein insofar as may be deemed necessary to complete the disclosure.

Having thus described my invention, I claim:

1. An article of manufacture comprising a hollow tubular member, a spiral fin helically wound on said tubular member, a plurality of radially extending folds formed in the base of the fin, and an integral foot on the fin extending along the inner periphery of said fin and tightly surrounding the outer periphery and extending axially of the hollow ember, the said foot comprising compressed portions of said folds overlapped circumferentially with respect to the outer periphery of said hollow member, the foot being formed throughout the entire contact between the fin and the tubular member to provide substantial mechanical support for the fin and increased heat transfer between the tubular member and the fin.

2. An article of manufacture in accordance with claim 1, in which the tubular member is provided with a plurality of axial flats extending along the outer periphery thereof, for cooperating with the foot to prevent unwinding of the fin from the tube.

3. An article of manufacture comprising a hollow tubular member, a spiral fin helically wound on said tubular member, a plurality of radially extending folds formed in the base of the fin, and an integral foot on the fin extending along the inner periphery of said fin and tightly surrounding the outer periphery of the hollow member and extending axially in opposite directions on either side of the fin, the said foot comprising compressed portions of the folds overlapped circumferentially with respect to the outer periphery of said hollow member.

4. An article of manufacture comprising a hollow tubular member, a spiral fin of ductile sheet material helically wound on said tubular member, a plurality of radially extending folds formed in the base of the fin, the thickness of the fin being less at the outer periphery of said fin than 4 extending axially in opposite directions on either side of the fin, the said foot comprising compressed portions of the folds overlapped circumferentially with respect to the outer periphery of said hollow member.

JOHN SHIPLlJY NEWLIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,394,311 Lang Oct. 18, 1921 1,734,136 Kramer Nov. 5, 1929 1,744,074 Gortner Jan. 21, 1930 1,840,317 Horvath Jan. 12, 1932 1,972,230 Lehman Sept. 4, 1934 1,997,197 Nigro Apr. 9, 1935 2,053,239 Forrer etal Sept. 1, 1936 2,117,445 Niemchek May 17, 1938 2,152,437 Lear 1 Mar. 28, 1939 

